This invention relates to test and measurement in data communications and more particularly to network topology determination.
In network test and measurement operation, it can be helpful to determining an accurate network connection topology for a user of a portable network test tool.
Current test tools indicate network topology by reporting the first device that the tool is connected to, by monitoring for discovery protocol (Link Layer Discovery Protocol (LLDP), Cisco Discovery Protocol (CDP), or other discovery protocol), hereinafter xDP. This first device indication as implemented by these tools presents numerous problems:
1. Incorrect test indication: The tools incorrectly indicate the topology if there is an unmanaged switch or hub (hereinafter, switch) between the tool and the managed switch.
2. Unable to detect rogue switches: The tools do not detect the presence of unwanted or rogue switch devices. The availability and proliferation of low cost, unmanaged switches (e.g., $35 for 5 Port 10/100/1000 switch) makes them deployable by non-IT staff introducing unwanted port expansion, addition of network devices, and lower network reliability.
3. Decreased user confidence: In the cases when the tools are linked to a known unmanaged switch (e.g. in front of the tool) the tools do not indicate its presence, instead indicating an immediate connection to the nearest managed switch. This obvious miss-indication erodes user confidence in other test results that the tools may provide.
4. SNMP reliance: In many situations SNMP (Simple Network Management Protocol) is not available due to either SNMP running on a separate management plane or that the SNMP community strings are not shared.